1. Field of the Invention
The present invention relates to a click-stop mechanism which is provided between two members, one of which is slidably fitted on the other.
2. Description of the Related Art
FIG. 10 shows a conventional click-stop mechanism provided between two cylindrical members of a photographing lens barrel. The lens barrel is provided with a stationary ring 30, and an AF/MF switch ring 31 fitted on the stationary ring 30 to be slidable thereon in an optical axis direction (in a direction normal to the page of FIG. 10) relative to the stationary ring 30. The AF/MF switch ring 31 can be manually moved between two positions (an AF position and a MF position) in the optical axis direction relative to the stationary ring 30 to select, e.g., between an AF (autofocus) mode and an MF (manual focus) mode of the photographing lens barrel, respectively. The AF/MF switch ring 31 is provided on an inner peripheral surface thereof with an AF-state holding groove (click-stop groove) 31a and an MF-state holding groove (not shown) each of which extends circumferentially about the optical axis.
The photographing lens barrel has a leaf spring 33 with one end thereof fixed to the inner peripheral surface of the stationary ring 30 by a set screw 32. The stationary ring 30 has a radial through hole 34 in which a click ball 35 is engaged. The click ball 35 is held between the AF/MF switch ring 31 and the leaf spring 33 so that the click ball 35 is always pressed against the inner peripheral surface of the AF/MF switch ring 31 by a spring force of the leaf spring 33. With this structure, the AF position and the MF position of the AF/MF switch ring 31 are defined by the engagement of the click ball 35 in the AF-state holding groove and the MF-state holding groove, respectively. In the case of providing the photographing lens barrel with an aperture setting ring having a structure similar to the above described structure of the AF/MF switch ring 31, the AF-state holding groove and the MF-state holding groove are replaced by a series of click-stop grooves 31b (shown by two-dot chain lines in FIG. 10) arranged at predetermined intervals in a circumferential direction of the AF/MF switch ring 31.
However, such a conventional click-stop mechanism increases the number of elements of the photographing lens barrel because at least one set screw 32 is necessary to fix the leaf spring 33 to the stationary ring 30. In addition, it is difficult to fix the leaf spring 33 to the stationary ring 30 because the leaf spring 33 has to be fixed to the stationary ring 30 from inside the stationary ring 30.
In another conventional click-stop mechanism using a compression helical spring instead of a leaf spring, a radially long insertion hole in which the compression helical spring is inserted needs to be secured. However, it is difficult to insert the compression helical spring into the long insertion hole.
The present invention provides a simple click-stop mechanism provided between two members, one of which is slidably fitted on the other, wherein the number of elements of the click-stop mechanism is small, and the click-stop mechanism can be easily assembled.
For example, a click-stop mechanism can be provided between two members, one of the two members being slidably fitted on the other of the two members, the click-stop mechanism including an engaging groove formed on one of opposed surfaces of the two members, a leaf spring insertion recess formed on the other of opposed surfaces of the two members, a click member which is engaged in the engaging groove so as to be movable in a direction normal to the sliding movement of the two members, and a leaf spring which is inserted in the leaf spring insertion recess to bias the click member toward the engaging groove.
It is desirable for the leaf spring insertion recess to include a pair of support portions formed in the leaf spring insertion recess to support opposite ends of the leaf spring, respectively, and a leaf-spring-deformation allowance portion which is positioned in the leaf spring insertion recess between the pair of support portions to allow the leaf spring to be resiliently deformed.
It is desirable for the other of the opposed surfaces of the two members, on which the leaf spring insertion recess is formed, to include a click member guide portion which allows the click member to move only in directions corresponding to directions of engagement and disengagement of the click member in and out from the engaging groove.
The engaging groove can be a plurality of engaging grooves which are formed on the one of the opposed surfaces of the two members at different positions in a direction of relative movement of the two members, and the click member can be selectively engaged in the plurality of engaging grooves.
The click member can be formed as a spherical click ball.
A portion of the click member which is engaged in the engaging groove can include a substantially semicolumnar portion having a ridge extending substantially in a longitudinal direction of the engaging groove.
Each of the two members can be an annular member provided in a lens barrel.
At least one of the two members is movable relative to the other in an optical axis direction of the lens barrel, and the engaging groove can include a plurality of engaging grooves which are formed on the one of the opposed surfaces of the two members at different positions in the optical axis direction.
The lens barrel can be used as a photographing lens barrel of an autofocus camera, and one of the two members can serve as a switch ring which is moved in the optical axis direction between an AF position and an MF position to change a focusing mode of the autofocus camera between an AF mode and an MF mode, respectively.
At least one of the two members is rotatable about an optical axis of the lens barrel relative to the other, and the engaging groove includes a plurality of engaging grooves which are formed on the one of the opposed surfaces of the two members at different positions in a circumferential direction about the optical axis.
It is desirable for the engaging groove to have a substantially V-shaped cross section.
The pair of support portions can include a pair of stepped portions formed on the one of the opposed surfaces of the two members in the leaf spring insertion recess to respectively support the opposite ends of the leaf spring.
It is desirable for the click member guide portion to include a pair of opposed recesses formed in the leaf spring insertion recess to hold the click member therebetween in the leaf spring insertion recess so that the click member can move only along the pair of opposed recesses.
In another embodiment, a click-stop mechanism is provided between two members, one of the two members being positioned on the other of the two members to be slidable thereon, the click-stop mechanism including two engaging grooves formed on one of opposed surfaces of the two members, a leaf spring insertion hole formed on the other of the opposed surfaces of the two members, a click member which is selectively engaged in one of the two engaging grooves so as to be movable in a direction normal to the sliding movement of the two members, and a leaf spring which is inserted in the leaf spring insertion hole to bias the click member toward one of the two engaging grooves.
The present disclosure relates to subject matter contained in Japanese Patent Application Nos.2001-177139 (filed on Jun. 12, 2001) and 2002-043173 (filed on Feb. 20, 2002) which are expressly incorporated herein by reference in their entireties.